Has my amp gone out?

I have a single amp with one 8" sub in my silverado (I'm not that inclined with audio stuff, so I don't know how much power the amp has or anything). The amp was a hand-me-down from my brother, so it's been around quite a while (I would say 10+ years).

About a week ago, I was on a 5-hour road trip, and all of the sudden my sub quit. I reached back and felt the amp, and it was pretty hot. I had driven that far in the past without issue though. Now, the sub doesn't come on at all. I checked all connections, and they are fine. Yesterday, I turned the stereo up really quickly, and it seemed to jump start it. The sub came on, but only for about 15 seconds.

Does this sound like syptoms of an amp that has bit the dust? Any help is appreciated!

I think something is putting the amp into protect mode First check the Fuses, But if it did turn on for a few then off again I would have a look at the Sub. If you can carefully push on it. Does it move smoothly? Or can you feel it hitting on the inside? If you have a meter test the Ohm's. What brand and model Amp and sub are they?

I agree, I second the woofer as the prime suspect. Chances are, your connections are good to go, the one connection I would verify is your ground connection. It needs to be short and grounded right to the body, no seat bolt, no existing bolt of any kind. Shave the paint next to your amp ground and ground it solid. Grounds become loose over time...well, some grounds, I through bolt mine to the body with stainless steel hardware, that's the best way to do it.

Sub looks good and doesn't bottom out if I push on it. It's an 8" RF Punch P2 (not sure if it's 2 or 4 ohm). The amp is a Sony XM-752X.

I checked the ground, and it's still solid. I already have it connected directly to the body near the amp.

I have everything mounted firmly, so nothing moves around (other than movement with the vehicle, obviously). I never abuse it and just crank up the volume. It's just to improve sound, not to vibrate the neighborhood. What's weird is that it happened randomly in the middle of a song, so I couldn't really see why it would go out like that. It's also weird that it came back briefly the other day.

Ok, try not to laugh too hard because this is going to be a dumb question....I have a multimeter but don't know how to use it. How would I go about checking the sub with a multimeter? If it's too complicated to explain, just say so, and I'm sure I can figure it out via internet searches.

Ok this is weird. I don't get a reading on the multimeter. But...I've tried to test things with it before and never got a reading, so it might be bad (I set it up according to the directions for the meter). The weird thing is when I had the stereo on, and I pushed lightly on the sub itself, it would work. It might keep working for a second when I took my hand off but only for a second. Seems like it is something with the sub, but what could it be? Something loose or is the whole thing shot?